Biology Lecture Notes for the Week of !0-11 to 10-17
Biology Lecture Notes for the Week of !0-11 to 10-17 BIOL 1305 - 010
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This 5 page Class Notes was uploaded by Sofia Romero on Sunday October 18, 2015. The Class Notes belongs to BIOL 1305 - 010 at University of Texas at El Paso taught by Hsin-i Lin in Fall 2015. Since its upload, it has received 73 views. For similar materials see General Biology - 15965 in Biological Sciences at University of Texas at El Paso.
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Date Created: 10/18/15
Biology Notes for October 1117 October 13 Lecture Metabolic pathways are linked Carbon skeletons are molecules with covalently linked carbon atoms that can enter catabolic or anabolic pathways Anabolism is reverse catabolic pathways Catabolism hydrolyzes polysaccharides to glucose Proteins are hydrolyzed to amino acids Lipids break down to fatty acids and glycerol Fatty acids can be converted acetyl CoA Gluconeogenesis is where citric acid and glycolysis can be reduced to form intermediates that can be formed glucose Acetyl CoA form fatty acids while citric acids intermediates can form nucleic acids Amounts of different molecules are maintained at constant levels called metabolic pools This is maintained through enzyme regulation Enzymes can be regulated by allosteric regulation feedback inhibition and alteration of transcription of genes Photosynthesis involves light reactions and carbon xation reactions Light reactions converts light energy into chemical energy in the form of ATP or NAPDH Carbon xation reactions that reacts with the ATP or NADH along with CO2 to form carbohydrates Light which is transformed in photosynthesis is a form of electromagnetic radiation and which travels as waves and photons The shorter the wavelengths the stronger the energy Color is re ected light from the surface Photons can be absorbed by a molecules by adding energy to a molecule and makes them excited Pigments are molecules that can absorb wavelengths Chlorophyll absorbs red and blue An absorption spectrum is a plot off light energy absorbed against wavelength An action spectrum is a plot of biological spectrum off an organism against the wavelengths to which its exposed Chlorophyll A and Chlorophyll B both absorb light energy A photosystem spans the thylakoid and is where light energy is converted into chemical energy It consists of antenna systems and a reaction system The pigments chlorophyll a amp b carotenoids are arranged in antenna system When chlorophyll absorbs light it enters an excited state then releases an electron returning back to its normal state Excited chlorophyll gives the electron that then become oxidized to quotnormal chlorophyllquot The electron acceptor is rst in an transport system in the thylakoids The nal electron acceptor is NADP which gets reduced ATP is produced through photophosphorylation There are 2 photosystems photosystem I and photosystem II Photosystem l absorbs light at approx 700 nm and passes an electron to NADP reducing it to NADPH Photosystem ll absorbs light at approx 680 nm produces ATP and oxidizes water molecules Noncyclic electron transport uses only photosystem 1 and produces ATP using an electron that passes from an excited chlorophyll back to the same chlorophyll The Calvin Cycle 1 The xation of carbon dioxide Carbon dioxide is added to ribulose 1 5 bisphosphate RuBP RuBP catalyzes the reaction A 6 carbon molecule forms which breaks into 2 3 carbon molecules The reduction of 3 phosphoglycerate to G3P Regeneration from G3P to RuBP Extra G3P is transported to the cytosol and converted into hexoses When glucose accumulates it forms starch There are 2 different types of organisms autotrophs and heterotrophs Autotrophs are photosynthetic organisms Heterotrophs rely on autotrophs for fuel I w N I Lecture 101515 There are 2 types of reproduction asexua reproduction sexual reproduction Cell division is used for reproduction growth and regeneration ln asexual reproduction all offspring are clones and the only genetic variances would be due to mutations ln asexual reproduction a unicellular prokaryote may produce by binary ssion Single cell eukaryotes reproduce by mitosis Eukaryotes also have the ability to reproduce sexually Trees also use asexual reproduction Gametes are required for sexual reproduction and one parent gives one gamete each to the offspring Gametes are used for meiosis a process of cell division Gametes and offspring have genetic differences from their parents In eukaryotic cells DNA is organized into chromosomes A chromosome consists of a molecule of DNA and proteins Somatic cells are cells that aren39t made speci cally for reproduction Each somatic cells contains 2 sets of chromosomes that happen in homologous pairs Homologous chromosomes code for the same gene Homologous chromosomes do not have an exact replica of each other There are 3 different types of sexual reproduction all involve meiosis The haptonic lifestyle where the zygotes only happens in the diploid stage and the cells produce gametes my mitosis Alternation of generations meiosis gives rise to haploid spores This happens in all plants and it turns a gametophyte into a sporophyte and gametes are formed by mitosis Diplontic life cycle where gametes only reach the haploid stage The random choosing of the diploid chromosome set is essential for cell reproduction This forms a haploid gamete that fuses to make a diploid cell so no 2 individuals have the exact same genetic makeup 4 events must happen for cell division The reproductive signal to initiate The replication of DNA Segregation distributing DNA to 2 new cells Cytokinesis the division of the cytoplasm and the nal separation of cells In prokaryotes cell division replicates the entire organism It grows in size Replicates DNA Separates DNAcytoplasm through binary ssion Many prokaryotes have a single circular molecule of DNA There are 2 important regions in reproduction Ori where replication starts Ter where replication ends Replication occurs through a replication complex of proteins As replication proceeds the ori starts moving toward the opposite end of the cell DNA sequences actively bind proteins for DNA segregation An actinlike protein provides a lament for ori and other protein to move Cytokinesis occurs by the pinching in of the plasma membrane The 2 cell walls are then synthesized and the cells are separated Eukaryotic cells divide by mitosis and then follow with cytokinesis Replication of DNA happens as long threads weave through the replication complexes DNA replication only happens during the S phase of the cycle In the segregation of DNA a copy of each chromosome ends up in each new cell Chromosomes become highly condensed in eukaryotes Mitosis separates them into 2 new nuclei Cytokinesis follows mitosis which is different in plant and animal cells The cell cycle is the period between cell divisions It39s divided into the M phase and interphase The M phase is reproduction The interphase is the long period in between M phases it begins after cytokinesis and before mitosis Interphase has 3 phases Gap 1 is a variable and a cell may spend a long time in this phase S phase is where DNA is replicated Gap 2 is where the cell prepares for mitosis and synthesizes microtubules for regenerating chromosomes ln mitosis one nucleus forms 2 nuclei with the exact same chromosomes Mitosis is continuous but can be divided into parts the prophase prometaphase metaphase anaphase and telophase During interphase only the nuclear envelope and nucleolus are visible and the DNA is not condensed Three structures then appear in prophase the condensed chromosomes centrosome and spindle Sister chromatids are 2 DNA molecules on each chromatid after replication Centromere is where the chromosomes are joined Kinetochores are protein structures on the centromeres used for chromosome movement The karyotypes of an organism show the numbersize of its condensed chromosomes The centrosome determines the orientation of the spindle apparatus its located in the cytoplasm close to the nucleus and consists of 2 centrioles Centrosome is duplicated during the S phase and each part moves forward Centrosomes serve as mitotic centerspoles Polar microtubules form a spindle and overlap in the center to keep thee 2 poles apart Kinetochore microtubules attach to kinetochores on the chromatids and sister chromatids attach on opposite halves of the spindle During prometaphase the nuclear envelope breaks down During metaphase the chromosomes then line up in the midline of the cell During the anaphase the separation of sister chromatids are aided by M phase cyclinCdK and cohesion is hydrolyzed by separase After separation the daughter chromosomes are moved to opposite of the end of the spindles 2 mechanisms to move chromosomes A protein at the kinetochores called cytoplasmic dynein hydrolyzes ATP for energy to move chromosomes along the microtubules towards the poles Kinetochore microtubules can also shorten drawing chromosomes toward poles Telophase occurs after the chromosomes are separated while the spindles separate chromosomes uncoil the nuclear envelope and nucleoli appear and 2 daughter nuclei are formed Cytokinesis is the division of the cytoplasm that differs in plants and animals lnn animal cells the plasma membrane pinches between the membrane to form a contractile ring of micro laments In plant cells the vesicles of the Golgi apparatus appear along the plane of cell division and fuse to form a membrane